The present invention relates to charge forming systems, and more particularly to an improved system for metering fuel to an internal combustion engine.
The past three quarters of a century have seen the development of the internal combustion engine evolve from a crude, erratic single cylinder prime mover into a multitude of engines spanning a vast array of sizes and types. Rotary, free-piston, in-line, opposed and radial designs are all in use. Practically every sort of valving arrangement has been implemented at one time or another; besides the dominant poppet valve, sleeve, rotary, swing and reed valves have all been used.
Although enormous energy and resources have been expended in exploring all of the conceivable mechanical configurations into which an internal combustion engine can be formed, such efforts are virtually dwarfed by the efforts which have been directed toward the development of a simple and economical charge forming system which will elicit near-maximum power from an engine, provide smooth operation at all combinations of speed and load conditions, give immediate throttle response and make efficient, economical use of fuel.
Unfortunately the latter desiderata are not all of the qualities which must be displayed by a practical charge forming system. The proper mixture must be provided whether the engine is hot or cold; and, if cold, an enrichment or "choking" of the engine must be provided for. The system must further be as simple as possible, and must be susceptible of economical manufacture. It must also be relatively trouble free and be serviceable by moderately trained personnel with the use of as little special equipment as possible.
Meeting these constraints has proved a continuing challenge to fully three generations of physicists, engineers, mechanics, craftsmen and tinkerers. Examples of systems which have been previously tried, and are generally related to the present approach are disclosed in many patents which have been issued over the years. For example, in U.S. Pat. No. 1,283,043-Battelle a carburetor is shown which feeds fuel as a function of both engine RPM and throttle position. U.S. Pat. Nos. 2,711,718-Spanjer and 2,585,171-Pyle show fuel metering systems of diverse sorts, although the Spanjer carburetor system is expressly designed for propane-type internal combustion engines.
Still other approaches have been tried; in U.S. Pat. No. 3,696,798 a fuel metering arrangement is shown which purports to manage fuel-air ratio through the use of a diaphragm-type controller which is responsive to air pressure on opposite sides of a throttle valve. Rice, in U.S. Pat. No. 3,825,239, discloses a complex system for controlling a fuel-air mixture by continuously sampling the mixture and burning it in a pair of sample jets. Electromechanical means within monitor flame characteristics and feed back appropriate signals to controlling apparatus. Still another approach is shown by Woods in U.S. Pat. No. 3,771,504 which comprises a fuel metering system executed using fluidic technology and in which throttle position is caused to vary as a function of metered fuel flow. In U.S. Pat. No. 3,596,643-Schweitzer there is shown an optimizing system for internal combustion engines that dithers engine parameters to detect a point of maximum RPM. While such a system is free of arbitrary, programmed characteristics it has inherent functional drawbacks.
Accordingly, it will be appreciated that many ingeneous systems and components have been constructed, and after more than seven decades of effort charge forming systems for internal combustion engines have attained a high degree of development. However, new demands and constraints upon charge forming systems continue to be made. In particular, it is necessary to drastically lessen the amount of pollution emitted by internal combustion engines. The task of lessening the emissions from an internal combustion engine ultimately falls upon its charge forming system.
In an attempt to accommodate the latter-day, increasingly stringent requirements upon emissions from internal combustion engines scientists, engineers and others have been urged to new efforts to develop a superior charge forming system. The upshot has been a series of highly modified systems in which a conventional carburetion or fuel injection system is caused to operate in an extremely lean mode. The inadequacy of such modified systems is well known, fuel economy often suffering as a result of the modified system characteristics. The power and throttle response of production automobiles and trucks has also been detrimentally affected by the modifications.
In an effort to overcome the deficiencies of the modified systems newer, more complex systems have been developed. The latter systems are effectively "programmed", by the use of electronic circuits or otherwise, to synthesize signals for controlling the operation of an engine in response to perceived operating conditions in accordance with a predetermined scheme. The initial success of such systems, however, is dependent upon the ability of the system to synthesize the proper signals and the nature of the functional relationships within the system; their long-term success depends heavily upon the trouble-free operation of the complex system stages.
Accordingly, it will be appreciated that it would be desirable to provide a charge forming system for an internal combustion engine which provides smooth, responsive engine operation and minimizes both fuel consumption and the production of harmful pollutants.
It is therefore the object of the present invention to provide a self-calibrating charge forming system for an internal combustion engine.
It is another object of the invention to provide a charge forming system for an internal combustion engine which allows rapid response over a broad range of operation while maintaining the fuel-air ratio leaner than the stoichiometric ratio.
Another object of the invention is to provide an improved charge forming system in which the air-fuel ratio is controlled in response to manifested engine power output.
Still another object is to provide a fuel metering system which maintains an optimum fuel-air ratio over a broad range of engine operation.
Yet another object of the present invention is to provide a fuel and air metering system which meters fuel and air flow as a function of both a manual input and a manifestation of engine power.
Another object is to provide a metering system which continuously controls the fuel-air mix in response to a perceived manifestation of engine operation.
Another object of the present invention is to provide self-optimizing fuel and air flow controls adaptable for use with any lean burning stratified charge engine.
Still another object is to provide a charge forming system which is adaptable for use with a broad range of liquid fuels.